Tillage of the soil is possibly one of the most controversial areas of gardening. There are advocates for double digging, no-dig and every shade between. We lean towards minimal tillage; that is the minimum amount required to obtain economic yields. Ignoring the special case of garden establishment, which is covered elsewhere, we follow this program. Immediately prior to establishing a deep rooting crop, such as carrots, we lever a fork through the soil to shatter it deeply, but not invert it. Then the surface is hoed with a Coleman hoe, Canterbury hoe or GR wheel-hoe to create a seedbed. When compost needs to be incorporated, it is applied immediately prior to the forking. Crops that are in the ground a long time and that are hoed frequently to control weeds, are planted directly into a very coarse bed.
Double digging requires loosening the soil to the depth of two lengths of the digging spade, or fork. First a trench is made the width of the garden bed and the soil moved to the end of the bed where digging will finish. The soil at the bottom of the trench is forked, or spaded over, then the top spit of the next trench thrown onto the loosened soil. Whereupon, you loosen the soil at the bottom of the trench... It is a lot of work. In many places the Jonathan Sturm garden, the subsoil is very stiff clay and the effort involved doing this every spring makes his mind spin.
One of the world's greatest advocate of zero tillage in the garden, Bill Mollison, developed his ideas, called Permaculture, here in Tasmania with David Holmgren back in the 1970s. My experience is that a few crops benefit from this approach, but most yield much lower than the minimal tillage approach he has adopted. The main thing is to avoid treading on the soil you have tilled, unless you place a large sheet of exterior grade plywood on the garden bed first. One gardener contemptuously calls most gardening "farming footprints".
Gardening is made very much easier when the correct tool is selected for the job. Quality is an important issue when selecting tools. There is nothing more frustrating than to have a tool break, or more likely bend, rendering it useless. Quality steel will last for many years beyond low quality. Several of my tools are probably as old as I am, and still giving sterling service. Tools such as these are readily purchased at garage sales and auctions, and so need not be expensive. Expensive new tools can be cheaper than they seem. I took an expensive garden fork that broke back to the shop from which I purchased it 18 months before. The fork was replaced with the comment that this brand of fork did not break!
Maintenance of tools is important to keep them efficient and to maintain your investment. Keep them under cover when not in use and oil the steel parts with old sump oil or similar to keep them from rusting. Rubbing linseed oil into wooden handles helps to keep them tough. Hoes and spades can be sharpened with a bastard file for ease of cutting. Scythes are best sharpened with a knife steel such as butchers use to keep their knives razor sharp.
Despite the complexity of gardening, a small range of high quality tools is all that is required. There is a plethora of gadgetry introduced onto the market each year, designed more to make money for the seller, rather than to fulfil the advertised claims. The main tools are a spade, fork, rake and trowel. The spade can serve the place of a shovel if necessary, though I own a shovel that can serve as a spade. A conventional shovel makes a poor spading implement, due to its pointed shape. The Canterbury hoe is also good: it's a garden fork, but with the tines at an angle to the handle similar to a hoe.
Many gardeners prefer a garden fork for spading the soil. Try to use either implement to break the soil without inverting it. With the spade, this necessitates throwing the soil forward slightly, so that it breaks into its constituent crumbs. The tines of a fork can be levered through the soil to aerate it and achieve a similar result without throwing. Some growers lift the soil with the fork and gently hit the clump with it to break it.
Two specialised garden forks are available that implement the aeration technique. The first is called the 'U' bar, and its dimensions are included to allow you to have one fabricated. The second is based on a Dutch market gardeners fork and is commercially available in Australia. Also available is a more conventional garden fork with rather flattened tines. This is useful where quantities of partially decomposed compost need to be lifted and moved.
One tool I find particularly useful is the claw hoe. This is used as a substitute for the garden fork in reworking raised garden beds. It is rather quicker to use than an ordinary garden fork. It is also useful for harvesting potatoes grown by the conventional ridge method.
The garden rake is often used as a sort of miniature claw hoe, but they are not really sturdy enough to take this sort of punishment. Rakes are intended to be dragged across the soil to create the final fine tilth for seed sowing and to flatten the soil surface. Also, this drags larger clumps of soil and pieces of organic material off to the side. The bow rake is generally sturdier than the ordinary sort.
Hoes come in several forms. They are mainly used to break the soil surface, aerating and killing weeds at the white wire stage of growth. Kept sharpened with a bastard file, they will also cut through more mature weeds, which will kill annuals. The Dutch is pushed through the soil, rather than the chopping action of the ordinary hoe. One also works away from the worked area, rather than into it, making for a neater result in conventional row gardening. The onion hoe is useful where hoeing between closely spaced plants is required.
Scythes make very efficient mowers of long grass, particularly useful when cutting large areas for compost material. The handles on the snathe of a scythe are on a reverse screw thread (they unscrew in a clockwise direction) and can be loosened and repositioned for comfort. The appropriate way to use a scythe is best learnt from an experienced practitioner, but I will attempt to describe the method here. The blade is moved through the grass in a slicing, rather than chopping, action. Chopping is harder work and risks breaking aluminium snathes. The blade should be kept parallel to and slightly above the ground. The effort for moving the scythe comes from twisting the torso, utilising the strong muscles of the body as well as shoulders. A long, narrow cut is best.
While a garden tiller may save labour, it is also very expensive and unlikely to return its cost to the home gardener. Tillers require the gardener to increase the area under cultivation, compared to raised bed gardening, in order to produce the same amount of produce. This is not to say that they are not useful for initial preparation of the soil when beginning a garden, since this is the most labour intensive part of gardening.
Tillers come in two forms. The smaller tillers are propelled by the action of the rotating blades in the soil. To control the forward motion, the user pushes on the handles, which increases the friction between the depth skid and the soil. They are very tiring to use on this account. The other sort has wheels driven by the motor independently of the rotating blades. The better ones also have wheel brakes or clutches to make steering easier. They cost a lot more than the blade driven hoes and are more powerful. This sort also often allows the attachment of implements other than the rotating hoe. They are in fact single axle tractors.
Attachments for single axle tractors include blade ploughs, potato ridgers, disk cultivators, trailers, manure spreaders, mulch mowers, finger mowers, and sprayers. Their chief advantages over four wheel tractors include: no looking behind to monitor progress (very bad for the back), less soil compaction due to the lower weight, which in turn reduces the number of cultivations required, lower fuel consumption, lower capital cost and a smaller turning circle at the end of rows, thus using the land more efficiently. Their chief disadvantage is their slow speed.
Rotary hoeing has a big disadvantage. Tilling at a constant depth polishes the soil, creating a hard pan which plant roots find hard to penetrate. It also slows water drainage, leading to waterlogging. Used as hoes for mechanical weed control is justifiable, but there use as the main tillage implement is not good for the soil. As well as panning, they can pulverise the soil to create the semblance of good tilth. Rain and irrigation then caps the soil, necessitating further cultivation.
On a scale intermediate between simple hand tools and motorised ones, come the wheel hoes. They are used for between row cultivation and row seeding. Though they require more effort than tillers, they are not so noisy, use no fuel and last much longer. They are considerably quicker than simpler manual tools and are relatively inexpensive.